The making of Prey's Gloo Cannon

With its sprawling abandoned space station setting, hordes of shape-shifting mimics and bouts of weightless space exploration, there are many things about Arkane's Prey that're worth emailing home about. Much similar to BioShock's Rapture or Dishonored's Dunwall, it could be argued that the dystopian Talos 1 is as much a central character as lead protagonist Mogan Yu—and there's one less than orthodox method of exploration that's arguably the most fun: building makeshift climbing walls with the game's iconic amorphous semi-solid fluid-firing Gloo Cannon. 

"We kind of had this idea that we'd be able to build bridges and staircases and all kinds of platforming things with it," the game's lead system designer Seth Shain tells me. "The whole thing did originally start with this idea that it would be a device the scientists would use to incapacitate the aliens. It went through so many iterations. The very first name was actually the Goo Gun without the 'L', and I was adamant we call it that. I knew we didn't know what fiction was—I knew that I didn't know how we were going to theme it, we just knew it was this thing that shot out some kind of fluid that would harden over time. I was like: the only way we can describe this for now is 'goo'. 

"Over the course of development, we had all these different types of versions. At one point we decided it was going to be an amber gun, it was going to shoot amber-like fluid and then harden into solid, transparent amber. And then we went away from that and then eventually ended up saying: let's just put an 'L' in there and then it's the Gloo Cannon."

From the outset Prey wanted to do things differently, says Shain, and the Gloo Cannon, even in its earliest of forms, was central to that vision. As far back as the game's pre-production stage, Shain and his colleagues decided to craft a weapon that doubled up as a tool of sorts that would both help players problem solve and traverse the Talos 1 space station.

Shain suggests this decision threw up an interesting distinction between Prey and the Dishonored series—whereby Corvo and latterly Emily are hamstrung by the restrictive world in which they exist. Sure, players learn the ability to teleport around both Dunwall and Karnaca, but a combination of gravity and high reaching walls often prevent the player from accessing the far reaches of each game world in turn.  

"In the world of Prey, because you're on the space station Talos 1 and outside of that is space, everything has a ceiling," Shane explains. "With that, we knew that the bounds of the player were already set by the ceiling—we didn't need to worry about it, we could just let the player move through that space as fluidly as they could."

A cursory YouTube search throws up hundreds of Gloo Cannon-inspired mountaineering, whereby adventurous players scale the space station's highest bounds. Whereas this is great fun from the player's perspective, the idea that almost nowhere is off-limits by virtue of the Gloo gun inadvertently placed the game's artists under pressure during development. If players can reach just about every nook and cranny of any given level, then it's no surprise artists are determined to make those far-flung areas look pretty. 

Shain tells me an awfully cool-sounding alien power was even cut from the game off the back of this burden.  

"The artists hate it because they want every square inch of the station to be beautiful, and if the player can get somewhere high up, then they feel they need to make it look good," says Shain. "We also talked about the quality of spaces—not every space needs to be an A-quality space. Some spaces can be B or C quality, and there are areas that are super hard to get to, that we don't expect people to get to, but maybe they can. We're also not inviting them there, we're not putting something there that they want, but people are going there just to see if they can. 

"There was another power that we cut because we just couldn't make it work or make it fun, it didn't hit our quality bar. It was a power that would directly allow you to fly around the space. That one just amplified that problem. They were really happy when they cut that, you're mostly constrained to the walls with the Gloo gun. We were deeply committed to that level of mobility in the spaces and letting the player explore as much as their heart desired."

Unlike the game's conventional weapons, the Gloo Cannon doesn't have a real-world template to work from. This is a weapon born from Arkane's imagination and what started out as a methodical, one gloo-ball-firing firearm quickly grew into a steady-shooting stream, flame thrower-like cannon. Shain explains the latter was too imprecise which meant it was too difficult for players to perceive range. This is also why the end product's rapid fire projectiles were settled upon.

These technical challenges made Arkane realise why such a weapon hadn't been created before—a fact that was galvanized by the Gloo Cannon's propensity for alpinism. Shain notes Shadow Complex's Foam Gun as one similar to the Gloo Cannon however also highlights the platformer's 2D makeup as something which allows for less logistical issues.   

"They were able to do something that we couldn't," admits Shain. "They were able to build their [foam] on top of [foam], so it's possible to build a platform from a wall. That's something that we couldn't do because it created this technical problem—this chain of constraints that added to the computation time to the whole chain. There was no way we could do this and have it perform on console, and so one of the constraints early that we learned for the Gloo gun is that: we can attach gloo to most things, but we can't attach gloo to gloo. 

"When we start doing that we get into a lot of trouble with hitting the bounds of what we can do technically. That's when we came up with the idea that there was certain surfaces that gloo bounces off of. This way we have this sort of design language for the player to understand that gloo doesn't necessarily attach to everything."

Since launch, this has hardly stopped players creating shortcuts or from scaling the heights of the Talos 1 lobby, but, given this weapon was designed initially as a tool for subduing enemy mimics, would crafting the likes of an ice-firing cannon have served the same purpose?

"The ice thing is kind of funny," says Shain. "I feel a little embarrassed to say this because it sounds naive but we were deep into this feature and we had implemented it where we were actually locking enemies down and what not. It then occurred to me one day where I was like: oh, this is like a freeze gun. But because our departure point when we started, in terms of what our direction was and what our goals were, was so far from ice gun or freeze gun that it wasn't on the forefront of our minds." 

BioShock's plasmids work in a similar way, and a quick fire combination of Ice followed swiftly by a forceful spanner melee attack was a guaranteed way to fell unsuspecting Splicers.  

"I mean, we weren't thinking about that, we were thinking about this tool that would immobilise enemies but that would also have orthogonal abilities that'd be useful for platforming," explains Shain. "Then all of a sudden we sort of convergently evolved into this notion that, oh yeah, it freezes enemies just like a freeze gun would. I think it's an important distinction: because we didn't start with the assumption this was going to be a different flavour of freeze ray, we started with the assumption that it was some kind of orthogonal tool that also has a combat implication that we were able to iterate to the point and discover all the applications and uses whereby you can attach its ammo to the walls or platforms."

Much like plasmids, then, or Dishonored's supernatural abilities, how players leverage the Gloo Cannon in concert with their learned alien powers opens the game up to much experimentation. My own mixture of choice involves pairing Lift Field with the Gloo Cannon, however Shain's is a little more enterprising still.

"One of my favourite things to do is use Lift, and lift up a big leverage object near a wall before gloo-ing that leverage object to the wall while it's lifting. When the lift toward dissipates, now you have a platform on the wall that attached with the gloo.

"There was this one moment I had during testing that was so fluid and natural that was the outcome of playing and responding to the systems. I was being chased by a phantom, I'd lifted a huge piece of machinery, I glooed it to the wall. The phantom then shows up to attack me and is standing under it—I pulled my pistol out, shot the gloo that was affixing it to the wall and the thing dropped and fell on the phantom and killed it. It was one of those sublime moments. Even as the systems designer on the game I wasn't even thinking that this was going to work."

With Prey now almost two months post-release, Arkane is currently hard at work on its proposed DLC. Shain remains tight-lipped about what exactly that entails, however is certain the archetypal Gloo Cannon has cemented its place in the game's future. 

"I don't have any definite news to share with any of that but I do think it's safe to say the Gloo Cannon is a really important feature in Prey and I think it'll always be an important feature in Prey," says Shain. "We like to talk about the key features of the game that really separate it apart. We know that Mimic is one of them and that Gloo Cannon is one of them."